Do all resonance structures need to be FC=0?

[Meera McAdam 1C]

For example, for the SO2 (subscript 2) structure, one structure has an overall FC=0, but two others have an overall charge of FC=-1. Why do we still count these as resonance structures if they are less stable? When drawing a lewis structure, how would I know how many resonance structures there are if they are different overall charges?

Thanks.

[Kathy Vu 3L]

Resonant structures are used to show delocalized electrons, therefore you would have to draw all the possible bondings, even if they are not stable. As for finding out how many structures to draw, I just look at all the possible places that the double/triple bond can go.

[Ishita_Dubey_2D]

Resonance is a combination of all possible structures of a molecule, even the ones that are less stable. Therefore, include structures with formal charges not equal to zero. The most prominent structure, however, will be the one with the lowest formal charges.

[Michelle Nguyen 2L]

All the possible resonance structures contribute to the form of the resonance hybrid; however, more stable forms (which occur where the formal charges of the bound atoms are closest to zero) contribute more to the resonance hybrid than less stable forms, and the more unstable a structure is, the less it contributes to the resonance hybrid.

[Kimberly Santander3L]

Resonance structures that at formal charge=0, means that it's a stable bond. Typically we want to have a bond that is the most stable, not all resonance structures will have a formal charge =0 and it doesn't mean that structure is incorrect just less stable.